Indeterminate Western Blot Patterns Research Articles

HTLV infection in HCV-antibody positive patients in Spain.

Since hepatitis C virus (HCV) and human T-lymphotropic virus (HTLV) share transmission routes, dual infection could be frequent. In Spain, HTLV underdiagnosis is highlighted by the high proportion of patients presenting either with tropical spastic paraparesis (TSP) or adult T-cell leukemia (ATL) at first diagnosis. We examined whether the renewed efforts for expanding HCV testing may provide a sentinel population that might selectively be targeted to unveil asymptomatic HTLV carriers. The presence of anti-HTLV antibodies was examined in 3,838 consecutive individuals with reactive HCV serology attended during the last three years at 13 hospitals distributed across the Spanish geography. Overall 71% were male and the median age was 41-years old. Foreigners represented 9% of the study population. A total of 50 individuals (1.3%) were seroreactive for HTLV, being 30 confirmed as HTLV-2 and two as HTLV-1 (0.12%). The remaining 18 had indeterminate Western blot patterns. Most individuals with HTLV-2 and HTLV indeterminate serology were HIV-positive, former injection drug users and native Spaniards. In contrast, the two HTLV-1 infections were found in men coming from Brazil and the Dominican Republic, respectively. In summary, the overall prevalence of HTLV infection in individuals living in Spain seropositive for HCV is 1.3%, more than 10-fold greater than in general outclinics in Spain. However, immigrants from HTLV-1 endemic regions and former injection drug users with HTLV-2 infection are by far the major contributory groups in HCV patients. Therefore, testing for HTLV in newly diagnosed HCV individuals would not contribute much to improve late HTLV diagnosis in Spain.

Low Proviral Load is Associated with Indeterminate Western Blot Patterns in Human T-Cell Lymphotropic Virus Type 1 Infected Individuals: Could Punctual Mutations be Related?

Background: indeterminate Western blot (WB) patterns are a major concern for diagnosis of human T-cell lymphotropic virus type 1 (HTLV-1) infection, even in non-endemic areas. Objectives: (a) to define the prevalence of indeterminate WB among different populations from Argentina; (b) to evaluate if low proviral load (PVL) is associated with indeterminate WB profiles; and (c) to describe mutations in LTR and tax sequence of these cases. Results: Among 2031 samples, 294 were reactive by screening. Of them, 48 (16.3%) were WB indeterminate and of those 15 (31.3%) were PCR+. Quantitative real-time PCR (qPCR) was performed to 52 HTLV-1+ samples, classified as Group 1 (G1): 25 WB+ samples from individuals with pathologies; Group 2 (G2): 18 WB+ samples from asymptomatic carriers (AC); and Group 3 (G3): 9 seroindeterminate samples from AC. Median PVL was 4.78, 2.38, and 0.15 HTLV-1 copies/100 PBMCs, respectively; a significant difference (p=0.003) was observed. Age and sex were associated with PVL in G1 and G2, respectively. Mutations in the distal and central regions of Tax Responsive Elements (TRE) 1 and 2 of G3 were observed, though not associated with PVL.The 8403A>G mutation of the distal region, previously related to high PVL, was absent in G3 but present in 50% of WB+ samples (p = 0.03). Conclusions: indeterminate WB results confirmed later as HTLV-1 positive may be associated with low PVL levels. Mutations in LTR and tax are described; their functional relevance remains to be determined.

Are seroindeterminate western blot patterns in human T-Cell lymphotropic virus type 1 (Htlv-1) infected individuals associated with low proviral load levels?

For HTLV-1/2 diagnosis, reactive screening results are generally confirmed by Western Blot (WB). However, the large number of indeterminate WB patterns is still a problem worldwide. The aim of this study was to determine whether low levels of proviral load (PVL) are associated with seroindeterminate results by WB. PVL was determined in 49 HTLV-1 samples confirmed by n-PCR and classified as G1: positive by WB from individuals with disease (n= 27, 5 ATLL and 22 HAM/TSP); G2: positive by WB from asymptomatic carriers (n= 18); and G3: seroindeterminate samples by WB from asymptomatic carriers (n= 4). The viral gen pol and albumin were quantified by real-time SYBR Green PCR (ABI Prism System-AppliedBiosystems 75). Calibration curves were constructed using a DNA stock from MT2 cell line (Limit of quantification: 3 pol copies/reaction-R2> 0.99) and the analysis was performed by Krustall Wallis (GraphPad Prism v.5). Median PVL values were 4.03, 1.58 and 0.15 copies of HTLV-1/1 PBMCs fo r G1, G2 and G3, respectively. Correlation between PVL and age of patients (S= 0.61) was found for G1 samples. PVL median values were significantly different between the three groups (p= 0.3); the difference was also observed (p = 0.5) when considering HTLV-1 positive samples by WB [G1 + G2] as a single group. Even though a seroconversion could not be discarded in seroindeterminate cases, a low viral replication rate due to other factors could trigger a weak immune response, thus causing seroindeterminate WB patterns. The present study clearly demonstrates that such cases could be associated to a low HTLV-1 PVL and that the molecular analysis is a necessary tool to reach a final diagnosis.

HTLV-I proviral load in Argentinean subjects with indeterminate western blot patterns

Methodology A total of 87 indeterminate WB samples (HTLV blot 2.4 assayGenelabs Diagnostics-) were studied over a 10 year period referred from the Blood Bank at Garrahan Hospital (n=83) and from the Virology Unit at Muniz Hospital (n=4). HTLV-I and –II tax and pol proviral sequences were amplified by in-house nested PCR assays. HTLV-I pVL was estimated by a quantitative real-time PCR assay targeting the HTLV-I pol gene and the albumin gene as normalizer. The limit of detection of the assay was 2.6 log10 copies of HTLV-I/106 PBMCs (0.04% copies/100 PBMCs).

Using a sensitive luciferase immunoprecipitation system (LIPS) to detect HTLV-I/II seroindeterminates in Jamaica

Human T-cell Leukemia Virus type I (HTLV-I) infects an estimated 15-20 million persons worldwide. A number of diseases have been associated with this virus including adult T-cell leukemia/lymphoma (ATLL), HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), HLTV-I uveitis, and HTLV-I–associated infective dermatitis. The screening process for HTLV-I among blood banks includes detection by an enzyme immunoassay (EIA) followed by a confirmatory western blot (WB). Seropositive results are defined by the presence of all core bands (p19, p24, and p53) as well as the band specific for recombinant HTLV-I Env glycoprotein. However, numerous cases have been documented in which a positive response was detected by ELISA, but WB displayed an incomplete banding pattern. These samples were then categorized as seroindeterminates. Using the LIPS assay, 60% of the 53 seroindeterminate samples previously screened by ELISA and WB displayed anti-HTLV-I Gag, Env or Tax antibody responses (based on 2 standard deviations above the mean value for the HTLV-I negative group). The LIPS assay was also able to detect anti-HTLV-I antibody responses in 6% of the 167 samples determined to be HTLV-I ELISA negative. A number of these samples were subsequently found to have an indeterminate WB pattern. Although the significance of these HTLV-I/ II seroindeterminates is unclear, it may suggest a much higher prevalence of exposure to HTLV-I/II than previously estimated, as seroindeterminate samples may indicate exposure to the virus. The LIPS assay is a sensitive and high throughput antibody detection assay which may prove to be a useful tool in HTLV-I related clinical investigations.

Epidemiological determinants and PCR results in Central African inhabitants with a new and frequent HTLV indeterminate Western Blot pattern exhibiting mostly p28, p32, p36, and a shifted GD21

Material and methods In the framework of ongoing projets on HTLV-1/2 and related viruses in central Africa, we systematically analysed by WB, plasma from villagers living in south Cameroun. The studied group included 2155 individuals (mean age 44, range 2-90, 982 women/1173 men), either Bantous (1258) or Pygmies (897). All plasma samples were tested by WB (HTLV 2-4 MPD) with interpretation done according to manufacturer instructions. Only clear bands were considered as positive/informative. DNA extracted from buffy-coat were subjected to PCR using several primer pairs known to detect HTLV-1/2/ 3/4. Positive PCR bands were sequenced.

Acute HIV-1 infection is highly prevalent in Ugandan adults with suspected malaria

Acute febrile illnesses consistent with malaria are the most common presentation at health clinics in sub-Saharan Africa, accounting for 30-50% of outpatient visits. The symptoms of acute HIV infection can mimic acute malaria. We investigated whether acute HIV infections could be identified among adults with suspected malaria at rural health centers in Uganda. A cross-sectional study of 1000 consecutive patients referred for malaria blood smears at each of seven government health centers, of which 2893 (41%) were 13 years or older and tested for HIV. HIV enzyme immunoassay antibody testing was performed on dried blood spots and confirmed by western blot. Enzyme immunoassay-nonreactive and enzyme immunoassay-reactive, western blot-unconfirmed samples were pooled (10/pool) and tested for HIV RNA by nucleic acid amplification testing. We defined acute HIV infection as HIV-1 RNA positive with a negative or indeterminate HIV-1 western blot pattern and early HIV infection as HIV-1 RNA positive with a positive western blot pattern, but with a BED-corrected optical density of below 0.8. Of 2893 patients evaluated, 324 (11%) had test results indicating HIV infection. Overall, 30 patients (1.0%) had acute HIV infection, 56 (1.8%) had early HIV infection, and 238 (8%) had established HIV infection. Acute HIV infections were more prevalent at sites with higher HIV prevalence and lower malaria endemicity. At multiple sites in Uganda, 1-3% of adults with suspected malaria had acute or early HIV infection. These findings highlight a major opportunity for expanding recognition of acute and early HIV infection in Africa.

Human T‐cell lymphotropic virus types I and II (HTLV‐I and ‐II) infection among seroindeterminate cases in Argentina

Human T-cell lymphotropic virus (HTLV) seroindeterminate cases have been reported among blood donors (BD) and in at-risk populations worldwide, including Argentina. The objective of the present work was to study the presence of HTLV-I/II infection and its association to specific Western blot (WB) patterns among healthy BD and at-risk populations in Argentina. We analyzed 83 HTLV-I/II seroindeterminate WB cases diagnosed among BD (n = 49) and in different at-risk populations (n = 34) for human retroviruses infections. Multiple indeterminate WB patterns were observed. Out of the total, 13.2% (11/83) of the cases were found to be HTLV-I/II positive by nested-PCR (n-PCR), including 13.2% (11/83) HTLV-I and 2.4% (2/83) presenting HTLV-I and -II co-infection. Most of their serological profiles showed reactivity to gag or env codified proteins. Two samples amplified only one of the six analyzed genes (1 HTLV-I pol gene and 1 HTLV-II tax gene). There was no association between the presence of Trypanosoma cruzi infection and an HTLV-I/II indeterminate WB pattern (only 3 of the 83 samples were positive for T. cruzi antibodies). In conclusion, the majority of HTLV-seroindeterminate WB donors lacked HTLV provirus and was thus considered uninfected. However, when seroreactivity to Env and Gag proteins are observed on the WB and especially in at-risk populations, HTLV infection should be suspected; such individuals should be followed-up and retested.

Prevalence of Human T-Lymphotropic Virus (HTLV) Antibodies Among the Donor Population in the State of Qatar

To determine the prevalence of antibodies to HTLV-1 & II among the donor population in Qatar and to evaluate the relevance of continuing routine pretransfusion screening of all donations for HTLV-I& II we surveyed all the results of the screening tests performed on 124,266 donations collected in the period August 1991 to the end of January 2004. All donations were screened by ELISA based assays and all donors who tested positive were recalled for repeat ELISA testing and confirmatory testing by Western-Blot (WB). Two hundred and sixty nine donors tested positive for HTLV-I/HTLV-II antibodies by ELISA but only 81 donors could be retrieved for confirmatory testing. On repeat ELISA testing 27 donors gave negative reactions; the remaining 54 were still positive and were tested by WB. Of those, 22 were confirmed positive by WB, 20 were WB negative while the remaining 12 donors gave an indeterminate WB pattern. Only one of the 22 W-B confirmed positive was a Qatari national The remaining 21 were non-Qatari donors belonging to various nationalities.

Hemopoietic stem cell transplantation from a donor with indeterminate HTLV‐1 status

American Journal of HematologyVolume 82, Issue 6 p. 495-495 Letters and CorrespondenceFree Access Hemopoietic stem cell transplantation from a donor with indeterminate HTLV-1 status Wing Y. Au, Wing Y. Au Department of Medicine, Queen Mary Hospital, Pokfulam Road, Hong Kong SAR, ChinaSearch for more papers by this authorEunice Chan, Eunice Chan Department of Medicine, Queen Mary Hospital, Pokfulam Road, Hong Kong SAR, ChinaSearch for more papers by this authorAlbert K.W. Lie, Albert K.W. Lie Department of Medicine, Queen Mary Hospital, Pokfulam Road, Hong Kong SAR, ChinaSearch for more papers by this author Wing Y. Au, Wing Y. Au Department of Medicine, Queen Mary Hospital, Pokfulam Road, Hong Kong SAR, ChinaSearch for more papers by this authorEunice Chan, Eunice Chan Department of Medicine, Queen Mary Hospital, Pokfulam Road, Hong Kong SAR, ChinaSearch for more papers by this authorAlbert K.W. Lie, Albert K.W. Lie Department of Medicine, Queen Mary Hospital, Pokfulam Road, Hong Kong SAR, ChinaSearch for more papers by this author First published: 23 August 2006 https://doi.org/10.1002/ajh.20741AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL REFERENCES 1 Au WY, Lo JY. HTLV-1-related lymphoma in Hong Kong Chinese. Am J Hematol 2005; 78: 80– 81. 2 Mangano AM, Remesar M, del Pozo A, Sen L. Human T lymphotropic virus types I and II proviral sequences in Argentinian blood donors with indeterminate Western blot patterns. J Med Virol 2004; 74: 323– 327. 3 Kikuchi H, Ohtsuka E, Ono K, et al. Allogeneic bone marrow transplantation-related transmission of human T lymphotropic virus type I (HTLV-I). Bone Marrow Transplant 2000; 26: 1235– 1237. 4 Goldman JM. A special report: Bone marrow transplants using volunteer donors—Recommendations and requirements for a standardized practice throughout the world—1994 update. The WMDA Executive Committee. Blood 1994; 84: 2833– 2839. 5 Au WY, Lie AK, Cheng VC. Hematopoietic progenitor cell transplantation from a donor with indeterminate human immunodeficiency virus antibody status. Transfusion 2005; 45: 819– 820. Volume82, Issue6June 2007Pages 495-495 ReferencesRelatedInformation

Discovery of a new human T-cell lymphotropic virus (HTLV-3) in Central Africa

Human T-cell Leukemia virus type 1 (HTLV-1) and type 2 (HTLV-2) are pathogenic retroviruses that infect humans and cause severe hematological and neurological diseases. Both viruses have simian counterparts (STLV-1 and STLV-2). STLV-3 belongs to a third group of lymphotropic viruses which infect numerous African monkeys species. Among 240 Cameroonian plasma tested for the presence of HTLV-1 and/or HTLV-2 antibodies, 48 scored positive by immunofluorescence. Among those, 27 had indeterminate western-blot pattern. PCR amplification of pol and tax regions, using HTLV-1, -2 and STLV-3 highly conserved primers, demonstrated the presence of a new human retrovirus in one DNA sample. tax (180 bp) and pol (318 bp) phylogenetic analyses demonstrated the strong relationships between the novel human strain (Pyl43) and STLV-3 isolates from Cameroon. The virus, that we tentatively named HTLV-3, originated from a 62 years old Bakola Pygmy living in a remote settlement in the rain forest of Southern Cameroon. The plasma was reactive on MT2 cells but was negative on C19 cells. The HTLV 2.4 western-blot exhibited a strong reactivity to p19 and a faint one to MTA-1. On the INNO-LIA strip, it reacted faintly with the generic p19 (I/II), but strongly to the generic gp46 (I/II) and to the specific HTLV-2 gp46. The molecular relationships between Pyl43 and STLV-3 are thus not paralleled by the serological results, as most of the STLV-3 infected monkeys have an "HTLV-2 like" WB pattern. In the context of the multiple interspecies transmissions which occurred in the past, and led to the present-day distribution of the PTLV-1, it is thus very tempting to speculate that this newly discovered human retrovirus HTLV-3 might be widespread, at least in the African continent.

Human T lymphotropic virus types I and II proviral sequences in Argentinian blood donors with indeterminate Western blot patterns.

Human T-cell lymphotropic virus (HTLV) seroindeterminate blood donors have been reported worldwide including Argentina. To investigate the significance of HTLV-I/II seroindeterminate Western blot (WB) patterns, we conducted an 8-year cross-sectional study. Of 86,238 Argentinian blood donors, 146 sera were reactive by screening tests. The WB results indicated that 20% were HTLV-I reactive, 8% HTLV-II reactive, 61% indeterminate, and 11% negative. The overall seroprevalence was 0.034% for HTLV-I, 0.014% for HTLV-II, and 0.103% for indeterminate. In 57 reactive specimens, HTLV-I/II provirus could be examined by type specific PCR for tax, pol, and env regions. When at least two gene fragments were amplified HTLV-I/II infection was considered confirmed. PCR results confirmed all WB seropositive samples for HTLV-I (n = 15), and HTLV-II (n = 7), and the only WB negative case was also PCR negative, showing a complete concordance between PCR and WB. However, of 34 WB seroindeterminate sera studied by PCR, in 5 was proviral DNA amplified. According to our criteria PCR confirmed one to be HTLV-I, and one HTLV-II, 3 remained indeterminate since only tax sequences were amplified. Among WB indeterminate samples tested by PCR, most of their serological profile showed reactivity to gag codified proteins but lacked env reactivities (70%). One sample with a WB gag pattern showed proviral tax sequences, but of the four samples with reactivity to env proteins GD21 (n = 3) or rgp46II (n = 1) PCR results indicated that one was HTLV-I, one was HTLV-II, and two were indeterminate (only tax sequences). In conclusion, the majority of HTLV-seroindeterminate WB donors exhibited a gag indeterminate profile lacking HTLV provirus, and were thus considered uninfected. However, seroreactivity to env proteins, in particular to GD21, may indicate infection and a follow-up study of each seroreactive blood donor should be considered.

Serological, Epidemiological, and Molecular Differences between Human T-Cell Lymphotropic Virus Type 1 (HTLV-1)-Seropositive Healthy Carriers and Persons with HTLV-I Gag Indeterminate Western Blot Patterns from the Caribbean

To investigate the significance of serological human T-cell lymphotropic virus type 1 (HLTV-1) Gag indeterminate Western blot (WB) patterns in the Caribbean, a 6-year (1993 to 1998) cross-sectional study was conducted with 37,724 blood donors from Guadeloupe (French West Indies), whose sera were routinely screened by enzyme immunoassay (EIA) for the presence of HTLV-1 and -2 antibodies. By using stringent WB criteria, 77 donors (0.20%) were confirmed HTLV-1 seropositive, whereas 150 (0.40%; P < 0.001) were considered HTLV seroindeterminate. Among them, 41.3% (62) exhibited a typical HTLV-1 Gag indeterminate profile (HGIP). Furthermore 76 (50.7%) out of the 150 HTLV-seroindeterminate subjects were sequentially retested, with a mean duration of follow-up of 18.3 months (range, 1 to 70 months). Of these, 55 (72.4%) were still EIA positive and maintained the same WB profile whereas the others became EIA negative. This follow-up survey included 33 persons with an HGIP. Twenty-three of them (69.7%) had profiles that did not evolve over time. Moreover, no case of HTLV-1 seroconversion could be documented over time by studying such sequential samples. HTLV-1 seroprevalence was characterized by an age-dependent curve, a uniform excess in females, a significant relation with hepatitis B core (HBc) antibodies, and a microcluster distribution along the Atlantic coast of Guadeloupe. In contrast, the persons with an HGIP were significantly younger, had a 1:1 sex ratio, did not present any association with HBc antibodies, and were not clustered along the Atlantic façade. These divergent epidemiological features, together with discordant serological screening test results for subjects with HGIP and with the lack of HTLV-1 proviral sequences detected by PCR in their peripheral blood mononuclear cell DNA, strongly suggest that an HGIP does not reflect true HTLV-1 infection. In regard to these data, healthy blood donors with HGIP should be reassured that they are unlikely to be infected with HTLV-1 or HTLV-2.

Prevalence of HTLV infection in pregnant women in Spain

Objective: To estimate the prevalence of HTLV infection among pregnant women in Spain. Methods:A commercial ELISA incorporating HTLV-I and HTLV-II antigens was used for HTLV antibody screening. Repeatedly reactive samples...

Evidence for a post-Columbian introduction of human T-cell lymphotropic virus [type I] [corrected] in Latin America.

To investigate the origin and dissemination of human T-cell lymphotropic virus type I in Latin America, we performed phylogenetic analysis on the LTR and env sequences of 13 HTLV-I isolates from Peruvians of four different ethnic groups: blacks and some mulattos of African origin; Quechuas of Inca origin; Nikkei of Japanese descendance; and Mestizos, a mixed population of white and Indian origin. All Peruvian samples could be situated within the cosmopolitan subtype HTLV-Ia, yet one sample showed an indeterminate Western blot pattern, lacking reactivity towards the HTLV-I type specific MTA1 peptide. Within the LTR, we could confirm the previously reported subdivision into four subgroups--one big transcontinental clade A, a Japanese clade B, a West African/Caribbean clade C and a North African clade D--and we identified a new separate subgroup E of black Peruvian strains. The clustering of the Peruvian samples seemed to depend on the ethnic origin of the host. The largest heterogeneity was observed in the black Peruvian samples. The mitochondrial DNA type of one of these black Peruvian strains of subgroup E was identical to that of West African source populations of the slave trade. Both findings support the idea of multiple post-Columbian introductions of African HTLV-Ia strains into the black Latin American population. Additionally, a tight cluster of Nikkei and Japanese samples implied a separate and rather recent transmission of a Japanese lineage of HTLV-I into Peru. A well-supported cluster of Latin American strains (including Peruvian Quechuas and Colombian Amerindians) could be situated within the transcontinental group. Molecular clock analysis of the Latin American and Japanese clade resulted in an equal evolutionary rate for those strains. Along with the anthropologically documented peopling of the Americas, the analysis was more in favour of a recent (400 to 100 years ago) introduction of HTLV-Ia into the American continent rather than a Palaeolithic introduction.

Intrafamilial clustering and 4-year follow-up of asymptomatic human T-cell leukaemia virus type I (HTLV-I) infection in Benin (West Africa)

Few data exist concerning familial human T-cell leukaemia virus type I (HTLV-I) carrier states and transmission in African countries. Two previous surveys performed in Benin in 1989 and 1990 using a three-level cluster sampling method allowed us to identify HTLV-I positive subjects. The evolution of HTLV-I within the families of these subjects is described over a 4-year period, 1991-1995. Since 1991, 37 HTLV-I seropositive subjects, six subjects with indeterminate Western-Blot pattern, and their relatives have been followed up once a year clinically and biologically. Twenty-three mothers in the study group gave birth to 27 children between 1991 and 1995. Among the 13 infants born to the 12 seropositive mothers, two seroconverted before their second birthday. One adult woman whose husband was seropositive developed seropositivity 4 years after marriage. In March 1992, a family case-control study (proband study) was conducted. A seroprevalence of 27.5% was found among 138 relatives of 32 infected subjects and 1.4% among 142 relatives of 32 control subjects. There is clearly an intrafamilial clustering of HTLV-I in Benin. The annual incidence density of HTLV-I in this cohort is estimated at 6 per thousand.

HTLV-I/II Indeterminate Serology and Natural Killer Cell Expansion

HTLV-I/II Indeterminate Serology and Natural Killer Cell Expansion

Author's Reply: Low HTLV-I/II Seroprevalence in Pregnant Women in Congo and a Geographic Cluster of an HTLV-Like Indeterminate Western Blot Pattern

Author's Reply: Low HTLV-I/II Seroprevalence in Pregnant Women in Congo and a Geographic Cluster of an HTLV-Like Indeterminate Western Blot Pattern

What is the situation of human T cell lymphotropic virus type II (HTLV-II) in Africa? Origin and dissemination of genomic subtypes.

Human T cell lymphotropic virus type II (HTLV-II) and its two genomic subtypes, A and B, which differ by 3 to 6% at the nucleotide level (depending on the gene studied), were until recently considered to be endemic only in certain Indian tribes in the Americas and were therefore considered mainly as a "New World virus." First, the evidence of HTLV-II antibodies and later characterization of isolates from sex workers or individuals living in large West and Central African cities suggested that HTLV-II subtype A could have been imported recently in Africa. However, the findings of HTLV-II infection in two Pygmy populations living in remote areas of Zaire and Cameroon suggest that HTLV-II might have been in Africa for a very long time. Furthermore, the discovery of HTLV-II subtype B virus in some of these Pygmies, but also in other individuals from Zaire and within a family in Gabon for three generations, confirms the hypothesis of a very ancient presence of this HTLV-II subtype B on the African continent Recent data indicate also that there exist in Central Africa specific HTLV-II divergent strains including an HTLV-II B variant strain in Gabon. In the context of recent evidence for interspecies transmission in Central and West Africa of HTLV-I/simian T cell lymphotropic virus type I (STLV-I) strains, leading to the two major HTLV-I African subtypes, we would like to suggest that some STLV-II (closely related to HTLV-II subtype B) still exist or might have existed in Central/East Africa. The recent finding of quite divergent primate T cell lymphotropic viruses (PTLVs) in several Pygmy chimpanzees of Zairian origin (PTLV-PP1664 and STLV-PP) and in wild-caught baboons in Eritrea, Ethiopia (PTLV-L), also supports the complementary hypothesis of a yet to be discovered new HTLV-II-related virus in humans. Careful study of the indeterminate Western blot patterns present in some populations in Central Africa strongly suggests that such an exciting possibility exists, thus opening new avenues of research on both the history of primate retroviruses and that of early human groups.

Detection of HTLV‐I and HTLV‐II infection in Africans using type‐specific envelope peptides

Antibodies to HTLV were determined in 4,630 black African individuals from Zaire, Ghana and South Africa; 185 (4%) were confirmed as seropositive. Seroprevalance was 0.2% in a group of South African women, 0.9% among Ghanaian refugees in Belgium and from less than 1% to over 15% in various sites and populations in Zaire. With the use of HTLV-I and HTLV-II type-specific envelope peptides, 93% of confirmed HTLV seropositives were classified as HTLV-I. Five persons from the Haut Zaire region had HTLV-II serological reactivities, suggesting the presence of HTLV-II or a related retrovirus in central Africa. A cluster of HTLV-I-like indeterminate western blot patterns lacking anti-p24 antibody was found in Bas Zaire.